Eight other people were struck by bullets when the shooting started at about 9 a.m. on the Fifth Avenue side of the building but those injuries are not believed to be life threatening, police said.

The two law enforcement officials spoke on condition of anonymity because they were not authorized to publicly discuss the matter. They said the gunman previously worked at a store inside the landmark skyscraper.

Crowds of tourists and people on their way to work gathered along 34th Street, which was shut down by police. Police helicopters buzzed overhead and swarms of officers were gathered around the crime scene.

Queens resident Rebecca Fox, 27, said she saw people running down the street and initially thought it was a celebrity sighting, but then saw a woman shot in the foot and a man dead on the ground.

"I was scared and shocked and literally shaking," she said. She said police seemed to appear in seconds. "It was like CSI, but it was real."

Hassam Cissa, 22, of the Bronx, said he saw two bodies on the ground, and police applying a white cloth to a man's stomach wound.

Gunshots so close to one of the city's leading tourist attractions immediately prompted fears of terrorism, but federal officials said that wasn't the case, and a guard at skyscraper said it didn't involve the parts of the building where tourists gather to visit the skyscraper.

The gunfire came less than two weeks after a knife-wielding man was shot dead by police near another tourist-saturated part of the city. Authorities say police shot 51-year-old Darrius Kennedy after he lunged at officers with a kitchen knife Aug. 12. Kennedy was smoking marijuana in Times Square on a Saturday afternoon when officers first approached, police said. It was the beginning of an encounter that would stretch for seven of the most crowded blocks in New York City.